Spooling machines customarily include a thread sensing apparatus to determine if the thread, yarn, or other filamentary material is within predetermined size limits. When the size limits are exceeded, that is, if the thread is too thick or too thin, the thread sensing element provides an "off-size" electrical signal which is applied to a cutting apparatus to cut the yarn or thread being spooled, so that defective pieces can be eliminated from the yarn or thread being spooled on the takeup package. Apparatus of this type require maintenance of an essentially constant filament tension. To determine the tension, a thread brake is placed in the path of the filament which is coupled to an automatic control arrangement to maintain the thread tension at a predetermined level with respect to a set reference.
If the filament being spooled should break which, in most instances, occurs just before it is being wound on the package, the tension is lost. Loss of tension distorts the position of the filaments in the thread quality or size sensing apparatus and causes the thread size sensing apparatus to provide an "off-size" signal. Consequently, the thread cutting apparatus will respond and cut the thread at the cutting position. The thread breakage, as noted, usually occurs between the thread brake and the takeup package, and thus stray remnant pieces of thread will appear in the machine, which have a length corresponding to the length of the filament between the actual break position and the cutter. The stray remnant pieces thus are positioned in the machine usually in that area which is used to knot thread which was cut because it was off-size to the remainder of the thread already spooled, or within the spooling mechanism itself. Removal of such remnant thread is difficult and it frequently happens that the stray remnants are carried along by subsequently spooled thread portions, to be wound up together with the yarn package which detracts from its overall quality.
It has been proposed to remove such stray remnant pieces by locating suction nozzles above and close to the yarn cleaning apparatus - that is, the apparatus which determines the size of the filament and provides an "off-size" signal if beyond tolerance limits. The suction nozzles continuously apply a suction air current on the filament being spooled, which applies an additional continuous loading thereon. The accessibility of the apparatus, particularly in the region where the filament passes through components thereof, is impaired; additionally, considerable energy is required to generate the necessary air suction, due to the high volume being handled. In spite of substantial energy use and component requirements, it still was not possible to reliably remove all stray remnant thread or yarn pieces.